One of the best tools that you have as gardeners to help us determine your gardening schedule is the USDA zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The earliest that you can plant missouri primrose in Helena can be figured out by using the USDA zone info.

Planting Calendar for Missouri Primrose

Frost tolerance for missouri primrose:	Tolerant of some frost.
When to plant:	Up to 5 weeks before last frost.

Missouri Primrose are one of those plants that can tolerate a little bit of cold weather which tells us that you can get them planted earlier than plants that are more sensitive to the cold.

The earliest that you can plant missouri primrose in Helena is March. However, you really should wait until April if you don't want to take any chances.

The last month that you can plant missouri primrose and expect a good harvest is probably August. If you wait any later than that and your missouri primrose may not have a chance to really do well. If you are starting your missouri primrose indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

On average the last frost when the weather gets warmer is on May 15 in Helena. In the coldest months of winter you can expect an average low temperature of -25°F.

Just be sure to remember that USDA zone info for Helena may not be accurate from year to year and the actual date of last frost changes from year to year. Half of the time in Helena it frosts late in the year after May 15 so be sure to be ready to protect your missouri primrose in the event of a late frost.

USDA Zone Info for Helena

Here is the info for USDA Zone 4b.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-25°F
Highest Expected Low	-20°F

This means that on a really cold year, the coldest it will get is -25°F. On most years you should be prepared to experience lows near -20°F.

Plants to Grow in Helena

You may be interested in your other planting guides for Helena.